Steering arrangement for articulated tracked vehicles

ABSTRACT

An arrangement for the steering and coupling together of two associated tracked units to form an articulated tracked vehicle set, includes a first upright for releasable coupling to a fixture on one of the tracked units, a second upright for coupling to a fixture on the other tracked unit, a first steering link which is connected in an articulated manner to the first upright about a first horizontal axis and a second steering link which is connected in an articulated manner to the second upright about a second horizontal axis, parallel with the first horizontal axis. The first and second steering links are mutually joined to a steering link unit about a steering pivot with a vertical axis of articulation. Hydraulic ram cylinder units are arranged so as to control relative turning movements between the first upright and the steering link unit, between the second upright and the steering link unit, and between the first and second steering links. The first upright is formed so as to be able to be anchored rigidly in one of the tracked units while the second upright is formed so as to be capable of rotation in bearings in the fixture on the other tracked unit about a longitudinal horizontal axis.

The present invention relates to an arrangement for the steering andcoupling together of two associated tracked units to form an articulatedtracked vehicle set.

In a previously known steering arrangement for an articulated trackedvehicle set, a front and a rear tracked unit are coupled together bymeans of a link mechanism which has an essentially vertical axis ofarticulation about which both tracked units can be turned relative toone another by means of a pair of hydraulic cylinders. The knownsteering arrangement has, by virtue of its design, certain limitationswith regard to characteristics such as steering geometry, controllablearticulation between the vehicle units, controllable damping of themovements of the vehicle units relative to one another and theuncoupling possibilities. In the development of larger and heaviertracked vehicle units such characteristics are of increasing importance.

One object of the present invention is thus to make available a steeringarrangement which makes possible better control of the articulationbetween tracked vehicle units of an articulated tracked vehicle set.

A second object of the present invention is to make available a rapidand simple means of coupling and uncoupling two tracked vehicle units.

A further object of the present invention is to make available asteering arrangement with improved steering geometry.

For the achievement of these objects, the steering arrangement accordingto the present invention is characterized in that it comprises a firstupright formed so that it can be releasably coupled to a fixture on oneof the tracked vehicle units, a second upright formed so that it can becoupled to a fixture on the other tracked vehicle unit, a first steeringlink which is connected in an articulated manner to the first uprightabout a first horizontal, transverse axis, and a second steering linkwhich is connected in an articulated manner to the second upright abouta second horizontal, transverse axis which is parallel with the firsthorizontal axis, and in that the first and second steering links aremutually joined to a steering link unit about a steering pivot with avertical axis of articulation, in that at least a first hydraulic ramcylinder unit is mounted on the first upright and connected to thesteering link unit in order to control relative turning movementsbetween the first upright and the steering link unit about the firsthorizontal, transverse axis, in that at least a second hydraulic ramcylinder unit is mounted on the second upright and connected to thesteering link unit in order to control relative turning movementsbetween the second upright and the steering link unit about the secondhorizontal, transverse axis, and in that at least a third hydrauliccylinder ram unit is connected between the first and second steeringlinks in order to control relative turning movements between thesesteering links about the point of articulation, in which the firstupright is formed so as to be able to be anchored rigidly in one of thetracked vehicle units and the second upright is formed so as to becapable of rotation in bearings in the fixture in the other trackedvehicle unit about a longitudinal horizontal axis. As a result of suchan embodiment of the steering arrangement according to the invention,the design permits the tracked vehicle units firstly to rotate relativeto one another about a longitudinal, horizontal axis, secondly to turnrelative to one another about two parallel, transverse horizontal axes,thirdly to be uncoupled with the whole of the steering unit remainingfixed to one of the tracked vehicle units, and lastly to be providedwith better steering geometry with the vertical axis of articulationpositioned centrally between the two tracked vehicle units which are tobe coupled together.

Further special characteristics and advantages of the present inventionare described in more detail below and in the following dependent patentclaims with reference to the enclosed drawings, in which:

FIG. 1 is a perspective view of a steering arrangement according to thepresent invention, seen obliquely from the rear;

FIG. 2 is a plan view of the steering arrangement in FIG. 1;

FIG. 3 is a partial cross-sectional side view of the steeringarrangement;

FIG. 4 is a cross-sectional side view of a constituent upright in thesteering arrangement according to the invention, which upright ismounted rigidly on a fixture intended to be attached permanently to oneof the two associated tracked vehicle units;

FIG. 5 is a perspective view of the fixture in FIG. 4;

FIG. 6 is a perspective view of the fixture and the upright in FIG. 4;

FIG. 7 is a cross-sectional side view of a part of an upright which isrotatable in bearings on a fixture intended to be attached permanentlyto the other of the two associated tracked vehicle units;

FIG. 8 is a side view of an alternative, simplified embodiment of theupright and the fixture in FIG. 4; and

FIG. 9 is an end view of the upright in FIG. 8.

In FIGS. 1 and 2, 10 refers generally to a first embodiment of asteering arrangement according to the invention, for an articulatedtracked vehicle set, not shown, comprising a front and a rear trackedvehicle unit. The steering arrangement 10 comprises a first upright 12which is intended to be mounted rigidly and releasably on a permanentlyattached fixture 14 on one of the tracked vehicle units. In theembodiment shown, the fixture 14 is intended to be mounted on the rearend of the front tracked vehicle unit of the set. The steeringarrangement 10 further comprises a second upright 16 which is intendedto be mounted so as to be capable of rotation on a permanently securedfixture 18 on the rear tracked vehicle unit. A first steering link 20 isattached to the first upright 12 so as to be capable of turning about afirst transverse horizontal axis A while a second steering link 22 isattached to the second upright 16 so as to be capable of turning about asecond transverse horizontal axis B. The steering links 20, 22 areconnected in an articulated manner to one another via a steering pivot24 with a vertical axis of articulation C and constitute a steering linkunit 26.

As is clearly shown in FIGS. 4 and 6, the first upright 12 comprises asleeve-shaped hub 28 with two essentially parallel, upright side pieces30 which between them and at the top support a hydraulic ram cylinderunit 32. A cylinder part 34 of this unit is mounted in a support 36which is mounted in bearings in the upper part of the upright 12 so asto be capable of rotation about a third transverse horizontal axis Ewhile an outer end of a ram piston part 38 of the hydraulic ram cylinderunit 32 is connected in an articulated manner to the steering link unit26 via a vertical steering peg 40 (FIG. 3) which protrudes coaxiallyfrom the steering pivot 24, i.e. is coaxial with the vertical axis ofarticulation C.

The second upright 16 similarly comprises a sleeve-shaped hub 42 (FIG.7) with two essentially parallel, upright side pieces 44 which betweenthem and at the top support a hydraulic ram cylinder unit 46. This has acylinder part 48 which is mounted in a support 50 which is mounted inbearings in the upper part of the upright 16 about a fourth transversehorizontal axis D which is parallel with the horizontal axes A, B and E.

The first, front steering link 20 has a fork-shaped front part, the legs20 a, 20 b of which straddle the hub 28 of the first upright 12 and arerotatably mounted on corresponding steering pegs 52 (FIG. 6) on the hub28, whereby the pegs 52 constitute the abovementioned first transversehorizontal axis A. Furthermore, the steering link 20 has an upright rearpart which comprises two vertically separated steering guide parts,namely an upper steering guide part 24 a and a lower steering guide part24 b (FIG. 3).

Correspondingly, the second, rear steering link 22 has a fork-shapedrear part, the legs 22 a, 22 b of which straddle the hub 42 of thesecond upright 16 and are rotatably mounted on corresponding steeringpegs (not shown) on the hub 42, whereby the pegs constitute theabovementioned second transverse horizontal axis B. The steering link 22also has an upright front part which comprises two vertically separatedsteering guide parts, namely an upper steering guide part 24 c and alower steering guide part 24 d. The steering guide parts 24 a and 24 c,and 24 b and 24 d of the steering links 20, 22, thus together constitutethe steering pivot 24 about the vertical axis of articulation C.

On the outside of the legs 20 a, 20 b of the first steering link 20,brackets 54, 56 are mounted to carry holders 58, 60 for the respectivehydraulic steering cylinder units 62 and 64. The cylinder parts 66 and68 of the respective steering cylinder units 62, 64 are mounted in anarticulated manner in bearings in the brackets 54, 56 about verticalaxes F and G, while their piston parts 70, 72 are connected in anarticulated manner to side brackets 74 and 76 on the second, rearsteering link 22. The steering cylinder units 62, 64 are arranged towork together in such a way that when the one piston part 70, 72 isdrawn into its cylinder part 66, 68, the second piston part 72, 70 isexpressed from its cylinder part 68, 66 so that the vertical steeringpivot is displaced to either side from its neutral position in FIG. 2.This allows the associated tracked vehicle units to be steered either toleft or right about the vertical axis.

The four parallel transverse horizontal axes A, B, D and E make itpossible for the steering arrangement 10, and hence the associatedtracked vehicle units, to perform vertical turning and articulatingmovements in which the horizontal axes A, B, D and E can act as guidepivots in a parallelogram so that the uprights 12, 16, and thus thetracked vehicle units can also perform mutually parallel movementsvertically. The hydraulic ram cylinder units 32, 46 are designed to actas hydraulic shock absorbers to damp vertical turning movements betweenthe tracked vehicle units during driving. These shock absorbersadvantageously also have an inbuilt function as active,pressure-adjustable manoeuvring rams by means of which the trackedvehicle units can, when required, be raised or angled upwards in order,for example, to surmount an obstacle.

In accordance with the present invention, the steering arrangementdescribed above is arranged to be attached rigidly and releasably to afixture in one of the tracked vehicle units and attached to a fixture inthe other tracked vehicle unit so that it is capable of rotation about ahorizontal transverse axis. In the embodiment shown (see FIGS. 4-6) thefixture 14 has a base plate 78 with a number of holes 80 to enable thefixture 14 to be attached to the rear of the front tracked vehicle unitby means of a number of screw fixings, not shown. From the base plate78, a horizontal, longitudinal, hollow bearing tube 82 protrudesbackwards, which bearing tube 82 is dimensioned to receive the hub 28 ofthe first upright 12. The bearing tube 82 and the hub 28 have matchingbayonet locking parts to make possible rapid securing and releasingbetween the fixture 14 and the upright 12 and thus the whole steeringarrangement 10. For this purpose, axially separated rows ofcircumferentially separated teeth 84 protrude close to the end portionof the bearing tube 82 while the hub 28 has, on its inner surface,complementary rows of teeth 86 which, by an axial movement of the hub 28over the bearing tube 82, can be inserted in the circumferentiallyseparated gaps between the teeth 84 on the bearing tube 82, after whichthe hub 28 in the case shown can be turned approximately 20° in ananti-clockwise direction, seen in FIG. 6, so that the teeth 86 then fitclosely in the axial gaps between the corresponding teeth 84 on thebearing tube, thus fixing the hub 28 axially on the bearing tube 82. Atthe same time, locking in the circumferential direction between thebearing tube 82 and the hub 28 can be achieved by the inside of theright hand side piece 30 of the upright 12 shown in FIG. 6 coming to thestop position against the face 88 of an axial locking tongue 90 on thefixture 14. A locking catch 92, which is mounted in bearings and free torotate about a pin 94 on the inside of the opposite side piece 30, canthen be swung down and wedged securely in position between the lastnamed side piece 30 and an opposing, slightly inclined face 96 of thelocking tongue 90. Release of the hub 28 from the bearing tube 82 isachieved by reversing this sequence of actions.

The fixture 18 for the opposite end of the steering arrangement 10comprises a base plate 98 with a number of holes 100 to enable thefixture 18 to be attached to the front of the rear tracked vehicle unitby means of a number of screw fixings not shown. From the base plate 98,a horizontal, longitudinal, hollow bearing tube 102 projects forwards,which bearing tube 102 is dimensioned to receive the hub 42 of thesecond upright 16 (see FIG. 7). In contrast to the rigid attachment ofthe steering arrangement 10 to the front fixture 14, the hub 42 isarranged to be permanently fixed in an axial direction and capable ofrotation in bearings on the bearing tube 102 in order thereby to permitsideways articulation of the front and rear tracked vehicle unitswithout subjecting the parts of the steering arrangement to undesiredtorsional loads.

As shown in FIG. 7, the hub 42 is mounted in bearings so that it canrotate on the bearing tube 102 over the slide bearing 104 while beingaxially locked on the bearing tube 102 by means of a nut 106.

In order to damp the mutual turning movements between the steeringarrangement 10 and the rear tracked vehicle unit about the longitudinalhorizontal axis H through the bearing tube 102, a transverse hydraulicram cylinder unit 108 is used, the piston 110 of which is connected inan articulate manner to the rear upright 16 and the cylinder 112 ofwhich is connected in an articulate manner to the associated reartracked vehicle unit. Like the hydraulic ram cylinder units 32, 46, thehydraulic ram cylinder unit 108 also has an inbuilt function as anactive, pressure-adjustable manoeuvring cylinder by means of which thewhole steering arrangement 10 can be turned about the axis H during theconnecting and disconnecting of the steering arrangement 10 to thefixture 14 on the front tracked vehicle unit, i.e. in order to lock andopen the bayonet lock 84, 86.

By means of the bearing tubes 82, 102 being hollow and the verticalsteering pivot 24 being situated above the longitudinal horizontal axisH, a universal drive shaft, not shown, for the transfer of power to thedriving tracks of the rear tracked vehicle unit can be locatedadvantageously to pass through these bearing tubes 82, 102.

The described steering arrangement 10 according to the invention is thusintended, with the tracked vehicle units in the uncoupled state, to becarried wholly on one of the tracked vehicle units, in the case shown onthe rear tracked vehicle unit. When the tracked vehicle units arecoupled together, the hydraulic ram cylinder units 32, 46, 108 and thesteering cylinder units 62, 64 can be manoeuvred as necessary in orderto guide the bearing tube 82 on the front fixture 14 into the hub 28 onthe front upright 12 and thereafter to turn the hub 28 throughapproximately 20° in order to lock the bayonet lock 84, 86 for the axialfixing of the steering arrangement 10 to the fixture 14. The lockingcatch 92 is then swung down into the space between the face 96 of thelocking tongue 92 and the inside of the one side piece 30. The lockingcatch 92 can be secured in position by means of a pin 114 (FIG. 6).

FIGS. 8 and 9 show schematically an alternative embodiment of the firstupright of the steering arrangement, namely the upright which isintended to be attached rigidly to the one tracked vehicle unit. Theupright 116 in this embodiment has essentially simpler design elementsfor the purpose of achieving a releasable, rigid attachment to thefixture on the front tracked vehicle unit. The upright 116 has, insteadof a hub, upper and lower fixing devices 118, 120 which can be attacheddirectly to the corresponding fixing devices on the tracked vehicleunit. The lower fixing devices 120 can be of the hook-on type so as tobe easily hooked onto the lower fixtures 122 on the tracked vehicleunit. The fixing devices 120 can for this purpose comprise adownward-pointing hook which can engage behind a locking piece 124 onthe tracked vehicle unit. A support heel 126 on the upper part of thelocking hook 120 can, in the mounting position, bear against a stay 128on the lower fixture 122. The upper fixing devices 118 comprise guidesfor a screw connection. Alternatively, although not shown in thedrawing, the upright 116 can have two upper and two lower fixing devicesof the same type as the fixing devices 118, whereby the fixing devicesof the hook-on type are omitted. Such an embodiment of the upright 116can thus in a very simple and rapid manner be attached rigidly to anassociated tracked vehicle unit by means of only two or four screws. Theupright 116 can generally be built up from two angularly bent sidepieces 116 a, 116 b (FIG. 9) and equipped with guide pegs 130 for asteering link, not shown, similar to the steering link in the firstembodiment. The angular bending of the side pieces 116 a, 116 b ispreferably such that a space 132 is created to allow for the passage ofa universal drive shaft 134. When the upright 116 according to FIGS. 8and 9 is coupled to the front tracked vehicle unit, the locking hooks120 are hooked first onto the locking pieces 124, after which theupright 116 is swung upwards with the hooks as a hinge and fixed withtwo screws at 118. In the alternative embodiments described above, theturning cylinder arrangement as well as the hub 28 and its associatedbayonet locking system 84, 86 (FIGS. 4 and 5), can be omitted from thedesign.

When mention is made, in the above-described embodiments of the steeringarrangement according to the invention and in the following patentclaims, of “horizontal” or “vertical” components and axes, this refersto an imagined neutral position of the tracked vehicle set when this isstanding on a horizontal surface.

Even if the described embodiments of the steering arrangement accordingto the invention relate to a variant in which the steering arrangementis attached rigidly and releasably to a fixture on the front trackedvehicle unit and attached rotatably to a fixture on the rear trackedvehicle unit, it is of course possible within the scope of the inventionto permit the steering arrangement to be permanently mounted on thefront tracked vehicle unit. It is similarly conceivable in the firstembodiment to reverse the locations of the bearing pegs and hubs, i.e.that the uprights have a hollow peg which can be inserted in asleeve-shaped hub on the respective fixings.

What is claimed is:
 1. Arrangement for the steering and couplingtogether of two associated tracked vehicle units to form an articulatedtracked vehicle set, characterized in that the arrangement comprises a)a first upright (12, 116), formed so that it can be releasably coupledto a fixture (14, 122) on one of the tracked vehicle units; b) a secondupright (16), formed so that it can be coupled to a fixture (18) on theother tracked vehicle unit; c) a first steering link (20) which isconnected in an articulated manner to the first upright (12, 116) abouta first horizontal, transverse axis (A); d) a second steering link (22)which is connected in an articulated manner to the second upright (16)about a second horizontal, transverse axis (B) which is parallel withthe first horizontal axis (A); that e) the first and second steeringlinks (20, 22) are mutually joined to a steering link unit (26) about asteering pivot (24) with a vertical axis of articulation (C); that f) atleast a first hydraulic ram cylinder unit (32) is mounted on the firstupright (12, 116) and connected to the steering link unit (26) in orderto control relative turning movements between the first upright (12,116) and the steering link unit (26) about the first horizontaltransverse axis (A); that g) at least a second hydraulic ram cylinderunit (46) is mounted on the second upright (16) and connected to thesteering link unit (26) in order to control relative turning movementsbetween the second upright (16) and the steering link unit (26) aboutthe second horizontal transverse axis (B); and that h) at least a thirdhydraulic cylinder ram unit (62, 64) is connected between the first andsecond steering links (20, 22) in order to control relative turningmovements between these steering links about the vertical point ofarticulation (C), in which the one upright (12, 116) is formed so as tobe able to be anchored rigidly in one of the tracked vehicle units andthe second upright (16) is formed so as to be capable of rotation inbearings in the fixture (18) in the other tracked vehicle unit about alongitudinal horizontal axis (H).
 2. Arrangement according to claim 1,characterized in that the second upright (16), which is formed so as tobe capable of rotation in bearings about a longitudinal horizontal axis(H) in a fixture (18) in one of the tracked vehicle units, can bemaneuvered by means of a fourth hydraulic ram cylinder unit (108) inorder to control mutual rotational movements between the upright inquestion (16) and the tracked vehicle unit.
 3. Arrangement according toclaim 1, characterized in that the third hydraulic ram cylinder unit(62) comprises two hydraulic manoueuvring cylinders coupled between thefirst and second steering links (20, 22), one of either side of theseand the vertical steering pivot (24).
 4. Arrangement according to claim1, characterized in that the vertical steering pivot (24) is arranged soas to lie essentially midway between the two tracked vehicle units whichare to be coupled together by the arrangement (10).
 5. Arrangementaccording to claim 1, characterized in that the first and secondhydraulic ram cylinder units (32, 46) are connected in an articulatedmanner with the steering link unit (26) about an axis which is coaxialwith the vertical point of articulation (C).
 6. Arrangement according toclaim 1, characterized in that the first of the uprights (16) has asleeve-shaped part (42) which is shaped so as to be inserted over abearing tube (102) on the fixture (18) in the one tracked vehicle unitso as to be fixed in an axial direction but be capable of rotation aboutthe bearing tube (102).
 7. Arrangement according to claim 6,characterized in that the second of the uprights (12) has asleeve-shaped part (28) which is shaped so as to be inserted over abearing tube (82) on the fixture (14) in the other tracked vehicle unitso as to be locked both axially and rotationally on the tube. 8.Arrangement according to claim 7, characterized in that thesleeve-shaped part (28) of the abovementioned second upright (12) isaxially lockable on the bearing tube (82) by means of a bayonet lockingarrangement (84, 86).
 9. Arrangement according to claim 7, characterizedin that the bearing tubes (102, 82) on the respective fixtures (14, 18)are hollow in order to permit a universal drive shaft to pass through.10. Arrangement according to claim 8, characterized in that the verticalsteering pivot (24) between the steering link (20, 22) is situated abovethe horizontal longitudinal central axis (H) between the sleeve-shapedparts (28, 42) of the respective uprights (12, 16).
 11. Arrangementaccording to claim 10, characterized in that the first and secondhorizontal transverse axes (A, B) intersect the longitudinal centralaxis (H).
 12. Arrangement according to claim 1, characterize in that thefirst and second hydraulic ram cylinder units (32, 46) are mounted inbearings on the respective upright (12, 16) so as to be capable ofrotation about horizontal transverse axes (D, E) which are parallel withthe first and second horizontal transverse axes (A, B).
 13. Arrangementaccording to claim 6, characterized in that the second of the uprights(116) is formed so as to be releasably attached to the associatedtracked vehicle unit by means of upper and lower fixing devices (118,120).
 14. Arrangement according to claim 13, characterized in that thelower fixing device (120) is of the hook-on type while the upper fixingdevice contains screw connections.
 15. Arrangement according to claim 1,characterized in that each of the first and second hydraulic ramcylinder units (32, 46) is formed as a combined pressure-adjustablemanoeuvring ram and hydraulic shock absorber.
 16. Arrangement accordingto claim 3, characterized in that the fourth hydraulic ram cylinder unit(108) is formed as a combined pressure-adjustable manoeuvring ram andhydraulic shock absorber.